Iterative Row Sampling

There has been significant interest and progress recently in algorithms that solve regression problems involving tall and thin matrices in input sparsity time. These algorithms find shorter equivalent of a n*d matrix where n >> d, which allows one to solve a poly(d) sized problem instead. In practice, the best performances are often obtained by invoking these routines in an iterative fashion. We show these iterative methods can be adapted to give theoretical guarantees comparable and better than the current state of the art. Our approaches are based on computing the importances of the rows, known as leverage scores, in an iterative manner. We show that alternating between computing a short matrix estimate and finding more accurate approximate leverage scores leads to a series of geometrically smaller instances. This gives an algorithm that runs in $O(nnz(A) + d^{\omega + \theta} \epsilon^{-2})$ time for any $\theta > 0$, where the $d^{\omega + \theta}$ term is comparable to the cost of solving a regression problem on the small approximation. Our results are built upon the close connection between randomized matrix algorithms, iterative methods, and graph sparsification.Comment: 26 pages, 2 figure

Fourlined Plant Bug (Hemiptera: Miridae), a Reappraisal: Life History, Host Plants, and Plant Response to Feeding

Phenology of the fourlined plant bug, Poecilocapsus lineatus, is presented for southcen- tral Pennsylvania; life history and habits are re-examined. Although breeding was previously thought to occur only on woody plants, we found that nymphs develop on numerous herbs. An extensive list of hosts, more than 250 species in 57 families, is compiled from the literature and the authors\u27 observations; preferences are noted for plants in the Labiatae, Solanaceae, and Compositae. Damage consists of lesions on foliage, the size and shape of the spots varying with leaf texture, pubescence, and venation. Plant response to feeding is immediately visible, the lesions seeming to appear simultaneously with insertion of the bug\u27s stylets. Histolysis of plant tissues, the most rapid response to mind feeding yet reported, is attributed to a potent lipid enzyme whose active constituents are under investigation

Hardy-Muckenhoupt Bounds for Laplacian Eigenvalues

We present two graph quantities Psi(G,S) and Psi_2(G) which give constant factor estimates to the Dirichlet and Neumann eigenvalues, lambda(G,S) and lambda_2(G), respectively. Our techniques make use of a discrete Hardy-type inequality due to Muckenhoupt

A Fast Algorithm for Well-Spaced Points and Approximate Delaunay Graphs

We present a new algorithm that produces a well-spaced superset of points conforming to a given input set in any dimension with guaranteed optimal output size. We also provide an approximate Delaunay graph on the output points. Our algorithm runs in expected time $O(2^{O(d)}(n\log n + m))$, where $n$ is the input size, $m$ is the output point set size, and $d$ is the ambient dimension. The constants only depend on the desired element quality bounds. To gain this new efficiency, the algorithm approximately maintains the Voronoi diagram of the current set of points by storing a superset of the Delaunay neighbors of each point. By retaining quality of the Voronoi diagram and avoiding the storage of the full Voronoi diagram, a simple exponential dependence on $d$ is obtained in the running time. Thus, if one only wants the approximate neighbors structure of a refined Delaunay mesh conforming to a set of input points, the algorithm will return a size $2^{O(d)}m$ graph in $2^{O(d)}(n\log n + m)$ expected time. If $m$ is superlinear in $n$, then we can produce a hierarchically well-spaced superset of size $2^{O(d)}n$ in $2^{O(d)}n\log n$ expected time.Comment: Full versio

Parallel Graph Decompositions Using Random Shifts

We show an improved parallel algorithm for decomposing an undirected unweighted graph into small diameter pieces with a small fraction of the edges in between. These decompositions form critical subroutines in a number of graph algorithms. Our algorithm builds upon the shifted shortest path approach introduced in [Blelloch, Gupta, Koutis, Miller, Peng, Tangwongsan, SPAA 2011]. By combining various stages of the previous algorithm, we obtain a significantly simpler algorithm with the same asymptotic guarantees as the best sequential algorithm

The external morphology of the egg and larval stages of Hemerobius stigma Stephens (Neuroptera: Hemerobiidae) with reference to life history and notes on a larval parasite

Identification of Hemerobius stigma Stephens is currently based only on adult morphological characters. This study provides additional morphological means to distinguish H. stigma from other hemerobiid species. The three larval stages of H. stigma can be distinguished by the number of setae present on the posterior annulet of abdominal segment 10 and the presence or absence of a trumpet shaped empodium. Taxonomic keys to the larval stages are included as well as life tables with notes on larval and adult feeding habits, fecundity, ovipositional preference and egg morphology. Ovipositional habits and life history data were recorded for Anacharus sp. (Figitidae), reared from parasitized H. stigma larvae

The Incidence of Postoperative Retching and Vomiting in the Adult Patient Undergoing Abdominal Surgery Following Intraoperative Administration of Droperidol

The complication of postoperative nausea and vomiting is still one of the most common today. The potential for secondary complications associated with retching and vomiting such as aspiration pneumonitis strain of suture line with possible hemorrhage, and potential fluid and electrolyte imbalance makes prevention of retching and vomiting a primary concern in the management of the postoperative patient. The use of antiemetic drugs to prevent or control postoperative nausea and vomiting is a long-standing practice. Droperidol, an antiemetic, routinely used since being introduced in 1963, has been found to be successful in treating postoperative nausea and vomiting. This study examines the effect of droperidol .018 mg/kg given intramuscularly one half hour prior to the end of anesthesia on postoperative emesis in the adult gynecological patient presenting for total abdominal hysterectomy. Twelve patients were in this double-blind study, six acted as controls and six were in the experimental group. All subjects were premedicated with morphine sulfate 0.1 mg/kg and glycopyrrolate 0.2 mg, intramuscularly administered. All were induced with pentathol 4 mg/kg preceded by curare 3 mg and followed by succinylcholine 1.5 mg/kg for intubation. The subjects were maintained on isoflurane, sixty percent nitrous in oxygen, and pancuronium for relaxation. The subjects were of similar age and weight. Duration of anesthesia was similar with a mean of 2.93 hours overall. The incidence of retching or vomiting was considered as the same result. The droperidol group had one subject retch only and another retch and vomit. This gave a 33 percent incidence of retching and vomiting. The control group had three subjects retch and vomit, giving a 50 percent incidence. The small sample size provided no statistical significance. The results showed a trend of decreased vomiting in the adult subject presenting for total abdominal hysterectomy. The routine use of droperidol in this particular population cannot be recommended from these results

The genus Sipha Passerini (Hemiptera: Aphididae) in North America

Five species of the aphid genus Sipha Passerini (Hemiptera: Aphididae) are reported in North America and are reviewed herein. Of these species, three are adventive species and include: Sipha elegans del Guercio, Sipha glyceriae (Kaltenbach), and Sipha maydis Passerini. Sipha maydis was discovered in California in 2007 and now has been found in Georgia. The genus also includes two native species: Sipha agropyronensis (Gillette) and Sipha flava (Forbes). Sipha maydis can be distinguished easily from all the other species in the genus that occur in North America because it is black. All the species except S. agropyronensis have been implicated in damage to crop plants. A key to the apterae and alatae of Sipha found in North America is included